The invention relates to a sensor, a preparation method and an application thereof, and a detection method of 2, 4, 6-trinitrophenol. The sensor comprises a substrate, a nano metal rod array vertically distributed on the surface of the substrate and molybdenum disulfide quantum dots loaded on nano metal rods, wherein the interval between every two adjacent nano metal bars does not exceed 1 nm, andthe average diameter of the molybdenum disulfide quantum dots is 2-4 nm. The sensor can emit green fluorescence with relatively high intensity, is high in human eye distinguishable degree, has wide universality and high efficiency, is high in fluorescence efficiency, can specifically recognize TNP, obviously quenches a fluorescence signal of to-be-detected TNP after the to-be-detected TNP is captured, is high in detection sensitivity, and can be used for detecting trace TNP.